GEC to copper water service question

[jc2254]

Hi All,

I am not an electrician. I am a facilities manager. I understand that the GEC must be attached to the water service before the first shut off valve.My first question is can I install a die-electric union after the valve? Second question,Do all of the copper pipes in a building need to be grounded via this GEC connection. Third question,Can I use a seperate grounding conductor that would be attached to the copper pipes that are on the interior of the building that would be connected to grounding rods?

 

[russ]

Re: GEC to copper water service question

Article 250.4(A)(4) Bonding of Electrical Conductive Materials and Other Equipment.

Electrically conductive materials that are likely to become energized shall be conected together and to the electrical supply source in a manner that estblishes an effective ground-fault current path.

Most inspectors require the water pipe to have jumpers around water meters, valves, and die electric unions.
Also refer to Artcle 250.52

The ground rods can be added to the waterpipe, but you must also be bonded to the ground that is bonded to the service neutral.

Russ

[ July 04, 2003, 09:45 AM: Message edited by: russ ]

 

[websparky]

Re: GEC to copper water service question

Also;

The GEC must be attached within the first 5' of entrance of the water supply. Then install a "jumper" around the metering devices.

If adding additional ground rods throughout the building, they all also must be bonded to all existing electrodes.

Dave

 

[dereckbc]

Re: GEC to copper water service question

JC2254

1. You can add a dielectric fitting to valve, but you would have to install a bonding jumper around it, so there is no point adding the dielectric.
2. All the pipes in you plant have to be bonded in case of accidental contact with energized circuits.
3. You can add as many grounding rods as you wish to make a ground electrode system. But they all have to be bonded to make a electrode system, not separate systems.

I gather from your questions you are trying to make some sort of isolated ground system or have problems with current flowing on interior water piping. Using separate ground systems will not make a quite ground system (only make it worse).

If stray currents are the problem then it is quite likely you have multi-grounded neutrals or ground references taken from different points along the electrode system, or the electrode system is not bonded to make a single system.

The key is to make an electrode system out of multiple electrodes, then make a single point connection to that system and distribute radially.

 

[bennie]

Re: GEC to copper water service question

Very good response Dereck. I like to think that a ground system should be designed with more care than the active load system.

The active line conductors when connected wrong will usually make it known by dumping the circuit.

A ground system with common mode current can go on forever. Correct routing and connecting points are the only solution.

 

[karl riley]

Re: GEC to copper water service question

jc: It would be helpful to know why you wanted to install the dielectric connector. The responses given here are correct, but if you are trying to prevent neutral return current from flowing out the building on the water supply pipe, then the answer is that you have to put in the dielectric outside the building. If 10' or more out, you don't have to do anything more. If inside 10', then you must add an additional ground rod or other electrode.

What is sometimes not realized is that the magnetic field from the current on the water pipe is duplicated from the service entrance cable, since the cable generates the same net current as the missing neutral current running on the pipe.
Karl

 

[jc2254]

Re: GEC to copper water service question

Thanks again for all of the info guys.
In response to karl Riley's reply....I want to install the die electric union after the valve and where the grounding wire is attached to the water service. I have a problem with pin hole leaks in copper pipes and I have found that there is a direct correlation between the amount of amperage that I can read with an amp meter and the amount of pin hole leaks.I figure by isolating the interior piping from the water service that has amperage on it would eliminate the effect that the current is having on the pipes.I am only trying to find a way to ground the interior piping in a way that would be safe and conform to code.

 

[don_resqcapt19]

Re: GEC to copper water service question

jc,
If you have current on the interior metal water piping system on the building side of the grounding electrode connection to the water pipe, then you have serious electrical problems within that building that need to be resolved. If these problems are not resolved before you isolate the interior piping from the under ground piping, you will create a very hazardous condition.
Don

 

[hurk27]

Re: GEC to copper water service question

This sounds like there is somthing useing the water pipes as a return (neutral) this is a very dangerous problem as Don has said. as isolating this pipe will allow the pipe to become engerzied to 120 volts. if the current you are reading is from the street side of the connection of the EGC then it is possable it is stray current caused by a weak or loss neutral down the road this current will not be present on the building side of the EGC connection only on the street side as this current is just trying to get to your neutral and not just run through the pipeing. I have never heard of current causing pin holes in pipe above ground in a building it is true that this can happen with under ground pipes as electrolis will cause it. but not when the pipe is supended in air?

 

[jc2254]

Re: GEC to copper water service question

Thanks guys!!!

My current is coming from the GEC that is attached to the city water service. If I remove the GEC from the water service there is no amperage on the water pipes,either coming from the street or on the interior after the valve. I would not leave the GEC disconnected but removed it to assure myself that this was the source of the amperage.The GEC was reconnected as soon as I was sure as to where the amperage was coming from.
Why would the GEC have aperage on it in the first place. I always figured that this was a ground connection and would or could not possibly have current on it.I have spoken to a couple of electricians and have gotten differing opinions so I figured that I would throw this question out here,where I see some obviously intelligent minds at work,and see how it pans out when matching what I see here and the opinions that i have gotten.

Thanks again.

 

[bennie]

Re: GEC to copper water service question

It is not uncommon for a water pipe to carry 1/3 of the total neutral load current. The loss of the water pipe will cause an increase in impedance, and a decrease in AFC. It will also decrease the EMF.

The earth worms and cows, will be more contented.

 

[jc2254]

Re: GEC to copper water service question

Bennie,
I hate to sound like a dummy but please explain your response in more detail.I could honestly use the help.
Thanks

 

[don_resqcapt19]

Re: GEC to copper water service question

I agree that from the GEC connection to the street, that the water pipe on a code compliant system will carry a portion of the grounded conductor current. The metal water piping system is required to be bonded to the grounded conductor at each building. This places the metal underground water pipe in parallel with the service grounded conductor and the current will divide between these paths based on the relative impedance of the paths. The most current will be on the path with the least resistance. The interior water piping system does not normally create a parallel path back to the utility transformer XO terminal like the underground water pipe does. If the interior piping has current there is likely a neutral to pipe fault where some of the branch circuit grounded conductor current is returning to the transformer XO terminal via the water piping system.
This problem should be checked out by a qualified electcial contractor as soon as possible.
Don

 

[bennie]

Re: GEC to copper water service question

Response deleted (under construction)

[ July 06, 2003, 04:57 PM: Message edited by: bennie ]